The present invention relates to the field of data verifiers and test apparatus and particularly to data verifiers for testing multiplexing systems such as telephone message metering apparatus.
In telephone systems, message metering equipment is useful for detecting and recording information about toll long distance and other types of telephone service. The equipment usually provides the capability of identifying and storing which line or which extension number on the line is the calling party. Such information is particularly desirable in telephone usage accounting and telephone usage engineering. Usage accounting is the function of identifying particular lines or extensions which place a call and assigning the responsibility for the cost of the calls to a particular department or person. Usage engineering is the function of providing communications engineers with call usage levels, grading indications, maintenance trends, and accurate loading figures for determining overall equipment requirements.
One message metering system capable of performing the above functions is described in the above cross-referenced applications and in U.S. Pat. No. 3,870,823.
Whenever message metering equipment is employed, it is desirable to periodically test the metering apparatus itself to facilitate detection of faulty operation before large quantities of erroneous data are collected. While the above-mentioned systems do contain error detection circuitry, additional and improved techniques are desirable for verifying the operation of message metering system and data multiplexing systems. In accordance with this background, it is an object of the present invention to provide an improved data verifying apparatus for use with telephone message metering equipment and other multiplexing systems.